1. Field of the Invention
This invention relates generally to drainage catheters adapted for use in draining a fluid from a body cavity and through a body conduit. Typical of such devices are urinary catheters that are adapted to drain urine from a bladder and through a urethra of a patient.
2. Discussion of the Prior Art
Urinary drainage catheters are used to provide an outlet for the urinary bladder when the normal outlet lumen (the urethra) is compromised or obstructed. Such catheters have been used on a more permanent basis, when the patient is incapable of controlling a capable urinary system due to sedation or lack of mental capacity. A typical urinary catheter is the Foley catheter, which is frequently used for bladder drainage. The Foley catheter is a thick-walled rubber tube with an inflatable balloon near its distal end. The catheter is inserted with the balloon deflated, through the urethra (which extends through the prostate and a bladder neck), and into the bladder cavity. When operably disposed, the balloon is inflated within the bladder cavity to a size that prevents the distal end from passing back through the bladder neck.
There are several disadvantages associated with this catheter and its method of use. Significant among these disadvantages is the construction of the Foley catheter, which typically is manufactured by dip-molding a solid mandrel. Providing the catheter with characteristics for resisting kinking is of particular advantage, but this necessarily requires a significant wall thickness. Foley catheters with a diameter of one-quarter inch or more are typical. This size of catheter is difficult to insert and very uncomfortable for the patient. Patient frustration sometimes leads to inadvisable patient removal, even with the balloon inflated. This of course can be very damaging and traumatic to the patient.
The hard rubber tip of a Foley catheter is also thought to contribute significantly to patient discomfort. As the bladder empties, it collapses and this hard rubber tip begins to rub against the wall of the bladder. The resulting irritation also contributes to patient frustration. Further discomfort results from the fact that the walls of the catheter must be relatively thick and somewhat rigid in order to resist kinking.
Catheters with inflatable balloons must of course provide for an inflation lumen. In a drainage catheter, the primary lumen must be large in order to accommodate the fluid being drained. In order to subtract as little space as possible from this primary lumen, inflation lumens have tended to be relatively small and consequently more susceptible to clogging. Particularly when this clogging results with the balloon inflated, there is no lumen through which the balloon can be deflated. When the Foley catheters of the past had been made from latex, it was possible to respond to a blockage by introducing mineral oil through the primary lumen to attack the latex material of the balloon. This typically results in balloon rupture, enabling the catheter to be withdrawn. Of course, many patients are allergic to latex, so this catheter material cannot be used in all cases.
While the normal flow of urine through the urethra functions as a sterilant, directing the urine through the lumen of the catheter leaves areas between the urethra and the catheter where urine can collect, ultimately resulting in infection. Unfortunately, infections in the urethra transfer rapidly into the bladder. Foley catheters have been provided with anti-bacterial coatings and carefully monitored to avoid infection.
A sphincter at the outward end of the prostate controls the flow of urine from the bladder into the urethra. In some cases, this sphincter is still capable of operation, although a catheter is required to traverse the prostrate. Under these circumstances, the Foley catheter has been undesirable, since its significant wall thickness, although advantageous for kink resistance, inhibits closure by the sphincter.
A Foley catheter is constructed with drainage openings at the distal tip and with the balloon disposed proximally of those openings. With the catheter operatively disposed and the balloon seated against the bladder neck, the openings are positioned well within the bladder cavity. As a result, the bladder does not fully empty, but rather is left with fluid that can be drained only to the level of the openings. This stagnant urine pool is thought to contribute to bladder infection.
These deficiencies of the prior catheters and methods are overcome with the present invention wherein a drainage catheter is provided with an elongate tube and a retention member, at least one of which is formed of a mesh. This construction enables the catheter to achieve a low insertion profile, and to provide maximum bladder drainage with no residual volume. The catheter has increased flexibility and a high degree of retention with reduced potential for damage if accidentally removed. Normal removal and replacement can be facilitated with the accommodation of a guidewire and obturator.
The retention member can be made from filaments that overlap and define interstices of the mesh. Latex need not be used in the manufacture of the catheter, so the product can be adapted for use even by those allergic to latex. Furthermore, the retention member need not include a balloon requiring an inflation lumen that is susceptible to clogging. Kink resistance is not a problem with the mesh construction, so the wall thickness can be minimal. As a result, the catheter is easily inserted and much more. comfortable for the patient.
Since urine passes outside, inside, and through the mesh, the catheter can facilitate normal urethra function. With the mesh construction, the prostatic sphincter can continue to control the flow of urine to the distal end of the urethra. Foreshortened catheters can also be provided to take advantage of an operable sphincter.
In one aspect of the invention, a drainage catheter is adapted to drain a fluid from a body cavity through a body conduit. The catheter includes an elongate tube having a proximal end and a distal end. A retention member is disposed at the distal end of the elongate tube and adapted for movement between a low-profile state facilitating insertion, and a high-profile state facilitating retention of the catheter in the body cavity. A woven mesh forms at least a portion of at least one of the elongate tube and retention member, the mesh being permeable by the fluid to facilitate drainage of the fluid into the elongate tube of the catheter.
In another aspect of the invention, the drainage catheter includes an elongate tube having a first wall extending between a proximal end and a distal end. A retention member is disposed at the distal end of the elongate tube and has a second wall adapted for movement between a low-profile state facilitating insertion of the catheter and a high-profile state facilitating retention of the catheter. First portions of at least one of the first wall and the second wall are woven and have properties for being permeable to the fluid. Second portions of at least one of the first wall and the second wall are woven and have properties for being impermeable to the fluid.
In a further aspect of the invention, the drainage catheter has an elongate tube and an enlargement member at least one of which has a low-profile state facilitating insertion of the catheter and a high-profile state facilitating operative disposition of the catheter. At least one of the elongate tube and the retention member has properties for automatically expanding from the low-profile state to the high-profile state.
A method associated with a further aspect of the invention relates to a process for inserting a drainage catheter. The catheter is provided with an elongate tube and a retention member at least one of which is formed of woven filaments heat set to a high-profile state. An obturator is placed into the catheter to move the catheter to a low-profile state. The catheter is then inserted and the obturator removed to permit the catheter to automatically return to the heat-set, normal, high-profile state.
These and other features and advantages of the invention will be more apparent with a description of preferred embodiments and reference to the following drawings.